The present invention relates to an intumescent composite comprising fire retardant materials having a restraining layer laminated thereto to dimensionally control the refractory char produced upon heating the laminated intumescent composite. The intumescent composite exists in a flexible rubbery form to the extent that it is not rigidized by the restraining layer. After exposure to intense heat or fire, the restrained composite intumesces and becomes a rigid char which has been dimensionally controlled by the restraining layer.
Prior art devices such as are disclosed in McMartin, U.S. Pat. No. 3,864,833 and Bradley et al., U.S. Pat. No. 4,061,344, have used intumescent material in the area of fire, vapor and smoke barriers. Co-pending U.S. patent application Ser. No. 54,742 relates to one type of flexible heat-expanding fire retardant composite materials with the intumescent component within an elastomeric binder. These composites have no directional control of their expansion and thus are optimally used within confined spaces. They are most effective in poke-through devices.